1. Field
The present disclosure relates to sensors and methods for detecting neutrons for research, medical, security and other applications.
2. Description of the Related Art
Neutrons are uncharged particles that can travel through matter without ionizing the matter. Because neutrons travel through matter in such a manner, neutrons are difficult to detect directly. Some other evidence of a neutron event must be detected in order to determine its existence. An indirect method detects the results of a neutron interaction event and not the neutron itself. For example, alpha and triton particles are emitted when 6Li captures a neutron, and give off energy that can be measured.
A scintillator is material that emits light upon absorbing ionizing radiation or energy from ionizing radiation. A scintillation counter measures this ionizing radiation. Generally, the counter includes a sensitive photomultiplier tube that measures the light from the fluorescent material. The photomultiplier tube is attached to an electronic amplifier and other electronic equipment to count and possibly quantify the amplitude of the signals produced by the photomultiplier. The subsequent multiplication of those electrons (alternatively referred to as photoelectrons) results in an electrical pulse that can then be analyzed and yield meaningful information about the particle that originally struck the scintillator.
Coded scintillation detectors are presently used in some neutron diffraction instruments. A powder diffractometer use end-on optical fibers to collect light and transport to photomultiplier tubes for coincidence coding. The small area and narrow angular acceptance of the fiber ends limit the light collection efficiency. The prospect of better light collection efficiency has driven several recent efforts in detector design for thermal neutron detection using wavelength-shifting fibers.